Patients taking the daily pill use it for a variety of reasons, topped by bone health. But new research in Friday’s British Medical Journal Online points toward greater susceptibility to another potentially fatal ailment.

WebMD notes that researcher Ian Reid, MD, of New Zealand’s University of Aukland, has conducted a new calcium-supplement study on almost 12,000 patients. His results found that regular intake of the pills caused a 20-to-30% spike in heart-attack risk. ABC News adds that a possible cause behind the heightened cardiovascular concerns is that the supplements stand to increase blood serum calcium levels.

But there is no universal code that all calcium patients can follow. The BMJ’s study was accompanied by an editorial on the role of the supplements in osteoporosis, which notes that no patient can experience the same benefits or risks from a daily calcium pill.

“Calcium supplements, given alone, improve bone mineral density, but they are ineffective in reducing the risk of fractures and might even increase risk; they might increase the risk of cardiovascular events, and they do not reduce mortality,” said Dr. John Cleland of the University of Hull in England and his colleagues in the BMJ editorial.

Past studies have gone in different directions, with calcium being touted as a predictor for heart attack risks. For more generic information on calcium, visit WebMD’s overview page.